Modern fitness apparatuses, or exercise machines, including treadmills, steppers, stationary bicycles, and the like are often electronically controlled to vary their resistance levels. For example, stationary bicycles are electronically controlled to vary their resistance over the duration of an exercise routine to simulate uphill, level and downhill riding conditions. This varies the routine, purportedly to prevent the user of the apparatus from becoming bored with the otherwise repetitive exercise.
At the same time, it is also known to measure the heart rate or pulse of the user and adjust the level of exercise accordingly to maximize the cardiovascular benefits achieved from physical exercise without wasting time and effort. This also provides the benefit of being able to quickly detect dangerously high or accelerating heart rates.
To this end, pulse detection circuitry has been coupled with exercise equipment which provides a display to the user and/or a supervisor corresponding to the actual heart rate being achieved. The user or the supervisor can then make adjustments to the resistance level to adjust the heart rate as needed.
In U.S. Pat. No. 4,998,725, a microprocessor varies the incline of a treadmill or the resistance to the pedalling of a stationary bicycle to achieve a target heart rate. Adjustment of the resistance is only generally disclosed as increasing the resistance to increase the heart rate and decreasing the resistance to decrease the heart rate.
Several types of exercise equipment have more than a single variable resistance mechanism that affects the user's heart rate. For example, conventional treadmills have both variable inclines and variable speeds, while many stationary bicycles have variable pedal resistance for the lower body as well as resistance-based exercise mechanisms for the upper body. Since numerous such mechanisms are often intended to be operated simultaneously, the resulting heart rate depends on the resistance of all operating mechanisms and their relationship to each other and to the heart rate. At the same time, the conditioning of the skeletal muscle groups being exercised depend on which resistance mechanisms are being varied. Although exercise equipment comprising interrelated resistance mechanisms have become increasingly popular, the prior art varies only a single one of the mechanisms to control heart rate. The results are unsatisfactory because achieving a target heart rate in such equipment by merely increasing or decreasing one of the resistance mechanisms does not consider and compensate for the benefits or detriments that may occur by varying the resistance of the other such mechanisms in relation thereto.